CSAR101 Module Week 1 PDF

COLLEGE OF COMPUTING AND MULTIMEDIA STUDIES Introduction to Architecture and Organization Organization and Architecture In describing computers, a distinction is often made between computer architecture and computer organization.  Computer architecture refers to those attributes of a...

COLLEGE OF COMPUTING AND MULTIMEDIA STUDIES Introduction to Architecture and Organization Organization and Architecture In describing computers, a distinction is often made between computer architecture and computer organization.  Computer architecture refers to those attributes of a system visible to a programmer or, put another way, those attributes that have a direct impact on the logical execution of a program. Examples of architectural attributes include: o the instruction set o number of bits used to represent various data types (e.g., numbers, characters) o I/O mechanisms o Techniques for addressing memory  Computer organization refers to the operational units and their interconnections that realize the architectural specifications. Organizational attributes include: o Hardware details (e.g., control signals) o Interfaces between computer and peripherals o Memory technology used Structure and Function A computer is a complex system; contemporary computers contain millions of elementary electronic components. But how can one clearly describe them? The key is to recognize the hierarchical nature of most complex systems, including the computer  A hierarchical system consists of interrelated subsystems, each with its own hierarchy down to the lowest level. This structure is used for both design and description, allowing designers to focus on one level at a time. Each level consists of components and their relationships, with behavior depending on simplified representations of lower levels. o Structure – How components interrelate.  Central processing unit (CPU)  Control unit: Controls the operation of the CPU and hence the computer  Arithmetic and logic unit (ALU): Performs the computer’s data processing functions  Registers: Provides storage internal to the CPU  COLLEGE OF COMPUTING AND MULTIMEDIA STUDIES  CPU interconnection: Some mechanism that provides for communication among the control unit, ALU, and registers  Main Memory  I/O: Moves data between the computer and its external environment.  System interconnection o Function – How each component operates within the system.  Data Processing  Data Storage  Data Movement  Control System description follows bottom-up (building from the lowest level) or top-down (breaking down from the whole system). Research favors top-down as clearer and more effective, describing computer systems from major components to lower levels.  COLLEGE OF COMPUTING AND MULTIMEDIA STUDIES Brief History of Computers The First Generation: Vacuum Tubes  ENIAC (Electronic Numerical Integrator and Computer)  The first general-purpose electronic digital computer, developed at the University of Pennsylvania to aid the U.S. Army during World War II.  Designed by John Mauchly and John Eckert, it used 18,000 vacuum tubes, weighed 30 tons, and performed 5,000 additions per second.  Unlike modern computers, it operated in decimal rather than binary and required manual programming using switches and cables.  Completed in 1946, it was later used for hydrogen bomb calculations and remained in operation until 1955.  Von Neumann Machine  Introduced the stored-program concept, allowing instructions to be stored in memory alongside data.  Developed by John von Neumann in 1945 for the EDVAC, it became the basis for modern computers.  The IAS computer (1952) was its prototype, featuring:  Memory storing both data and instructions  ALU (Arithmetic and Logic Unit) for processing binary data  Control Unit to interpret and execute instructions  I/O system for input and output operations  It followed a fetch-execute cycle, with 21 instructions for data transfer, branching, arithmetic, and address modification. This architecture remains the foundation of modern computers.  Commercial Computers  The 1950s marked the rise of the computer industry, led by Sperry and IBM.  UNIVAC I (1950) by Eckert and Mauchly was the first successful commercial computer, used for both scientific and business applications.  UNIVAC II (late 1950s) had better memory and performance, introducing backward compatibility to retain customers.  IBM 701 (1953) was IBM’s first electronic stored-program computer, focused on scientific applications, followed by the IBM 702 (1955) for business use.  COLLEGE OF COMPUTING AND MULTIMEDIA STUDIES  IBM’s 700/7000 series solidified its market dominance in computing. The Second Generation: Transistors The first major change in the electronic computer came with the replacement of the vacuum tube by the transistor. The transistor is smaller, cheaper, and dissipates less heat than a vacuum tube but can be used in the same way as a vacuum tube to construct computers. Unlike the vacuum tube, which requires wires, metal plates, a glass capsule, and a vacuum, the transistor is a solid-state device, made from silicon. The transistor, invented in 1947 at Bell Labs, sparked an electronic revolution, with fully transistorized computers becoming available by the late 1950s.  NCR and RCA were early leaders in transistor-based computers, with IBM following with its 7000 series.  The second generation of computers, marked by the transistor, featured improved performance, larger memory, and smaller size.  Key developments included more complex arithmetic/logic units, high-level programming languages, and system software.  The Digital Equipment Corporation (DEC), founded in 1957, introduced the PDP-1, marking the start of the mini-computer era.  The IBM 7094 o Part of IBM's 7000 series (1952-1964), saw an evolution in performance, capacity, and cost. Key improvements included:  Memory: Main memory grew from 2K to 32K words, and memory access time decreased from 30s to 1.4s.  Opcode Count: Increased from 24 to 185.  CPU Speed: Improved through transistor technology and complex circuitry. The Instruction Backup Register enabled prefetching, reducing average instruction cycle time. o Notable Features:  Data Channels: Independent I/O modules with their own processor and instruction set, allowing I/O operations to be offloaded from the CPU.  Multiplexor: Managed access to memory by scheduling tasks from the CPU and data channels independently.  COLLEGE OF COMPUTING AND MULTIMEDIA STUDIES The Third Generation: Integrated Circuits The integrated circuit (IC), invented in 1958, revolutionized electronics and marked the beginning of the third generation of computers. Prior to this, electronics relied on discrete components like transistors, resistors, and capacitors, which were individually manufactured and soldered to circuit boards, making the production process cumbersome and expensive. Microelectronics refers to the trend of shrinking electronic circuits, which is central to the development of modern computers. At the core of digital computers, two components are essential: 1. Gates (for data processing): Perform logical functions like AND, OR, etc. 2. Memory cells (for data storage): Store one bit of data. The integrated circuit consolidates components like transistors, resistors, and conductors into a tiny piece of silicon. Early ICs, known as small-scale integration (SSI), could contain only a few gates or memory cells. Over time, the number of components packed onto a chip increased, following Moore's Law, which predicted that the number of transistors on a chip would double every year, later slowing to 18 months. This increase in density has led to several key outcomes:  Cost reduction: The cost of chips has remained stable, while their capacity has increased.  Faster operation: Shorter electrical paths between components speed up processing.  Smaller size: Computers became more compact and versatile.  Energy efficiency: Reduced power and cooling requirements.  Reliability: Fewer interchip connections lead to more reliable circuits.  COLLEGE OF COMPUTING AND MULTIMEDIA STUDIES  IBM System/360 o Released in 1964 by IBM, the System/360 was a planned family of computers designed to cover a range of performance and cost levels. o Helped IBM solidify its position as a market leader with a 70% market share. o The architecture of the System/360 remains foundational in modern mainframe systems.  DEC PDP-8 o Released in the same year as the IBM System/360, the PDP-8 was a small, affordable minicomputer that could fit on a lab bench, priced at $16,000. o Far cheaper than the System/360, enabling lab technicians and OEMs to buy and integrate it into systems. o The PDP-8 sold around 50,000 units over 12 years, establishing the minicomputer market and making DEC a key player in the industry. o Featured the Omnibus bus structure, with 96 signal paths for control, address, and data, allowing flexible module configurations.  COLLEGE OF COMPUTING AND MULTIMEDIA STUDIES Later Generations Introduction of LSI, VLSI, and ULSI allowed for chips with increasing numbers of components (from 1,000 to over a million). As technology advanced, the classification by generation became unclear due to rapid product introductions and the increasing role of software and communication.  Semiconductor Memory o 1950s/60s used magnetic-core memory, which was fast but bulky, expensive, and had destructive readout. o In 1970, Fairchild introduced semiconductor memory, faster and nondestructive, though initially more expensive. o By 1974, semiconductor memory became cheaper than core memory. This led to smaller, faster computers and a drastic reduction in memory cost and size, leading to more accessible office machines and personal computers.  Microprocessors o Intel 4004 (1971): The first microprocessor, combining CPU components on a single chip. o Intel 8008 (1972): The first 8-bit microprocessor, more complex than the 4004. o Intel 8080 (1974): The first general-purpose 8-bit microprocessor, faster with a richer instruction set. o 16-bit and 32-bit Microprocessors: In the late 1970s and 1980s, microprocessors like Intel's 8086 and 80386 ushered in 16-bit and 32-bit capabilities.